Tank or reg issue(empire reg, maybe repl. w/ ninja/)?

Alright... I've been on the search for a tank that was/is the perfect feel for me mated to my markers. I've went through a few tanks in the last few months and my favorite is my empire 56/4500, as far as size goes.

However, when I first screwed the tank onto my gun, the tank unscrewed from the reg. when I was removing it, I contacted where I bought it and was told that was normal empire doesn't put loctite on their threads. That once I aired it, it would be all good and under pressure the reg would be tight. Filled the tank, used it one day..... everything all good, loved my set up.

Now, I am pretty finicky when it comes to air systems, so thats why I am asking this. When I stored the tank, I could of swore I left like 2400 in the tank. When I just looked at it,there was very litte in the tank, around 400 or so maybe. I hooked it to my axe and went to gas it up, and all I got was a sound as if there was a leak on the tank. I unscrewed the tank figuring the air was so low that nothing happened.

As I was putting the tank away,I heard a rattle, it sounds like it may be coming from the regulator, its almost as if a marble is rolling up and down a channel or something (the best way I could describe the sound, its a smooth rolling sound). If you turn it down it goes to the bottom, flip it over, goes to opposite side. I've never heard anything like this before on any tank that I have ever owned, I'm suppose to play tomm but I am a little leery to fill it. Is this normal? Is the regulator going bad? Do I have a homemade bomb on my hands?

I was kind of just thinking F' it and since I like the tank, throwing a ninja smp reg on it..... But if I dont "have" to spend the money, I'd rather not... any input? anyone?

Awesome, thank you. I figured it had something to do with the tank not having any air and that whatever it is is normally under pressure so I did not hear/feel it move once pressurized. I narrowed it down and believe its coming from the reg.

I was just confused because when I first received it, naturally their was no air in the tank and it did not do this. Also, my other tanks, when they are empty, they do not do this. But thanks for the information, I am a little at ease now for the fill.